Self-cooled oil well polish rod stuffing box



Sept. 23, 1969 L.. E. REEvEs 3,468,374

SELF-COOLED OIL WELL POLISH ROD STUFFING BOX Filed June 13, 1967 United States Patent O 3,468,374 SELF-COOLED olL WELL POLISH ROD STUFFING Box Louie E. Reeves, 113 W. Berry, Hobbs, N. Mex. 88240 Filed June 13, 1967, Ser. No. 645,719 Int. Cl. F01p 3/12, 5/10; F161' 15/02 U.S. Cl. 166-84 Claims ABSTRACT OF THE DISCLOSURE A cooling chamber is disposed coaxially between two packing chambers to form a housing adapted to receive a moving polish rod. Input and output supply lines having oppositely opening one-way valves communicate between the cooling chamber and the interior of the production tubing in an oil well to circulate the production uid through the cooling chamber as the pressure in the production tubing is altered by the pumping motion of the polish rod.

BACKGROUND OF THE INVENTION Field of the invention The invention pertains generally to oil well production equipment and in particular to a new and improved oil well polish rod stuing box employed in oil well pumping installations.

After completion of an oil well, it is usually necessary to pump the oil up from its subsurface deposit through the production tubing. For this purpose, a pump is generally positioned within the tubing below the level of the oil. The pump is driven from the surface by a pumping jack through a reciprocating linkage of sucker rods moving through the tubing. The upward movement of the sucker rods co-operates with the pump to lift the oil through the tubing and push it into an above surface ow line which is secured to the wellhead by a pumping T. The pumping T is equipped with means which provides packing about the reciprocating sucker rods to permit the sucker rod linkage to communicate between the pumping jack and pump through the pumping tee without the loss of any of the oil which is being produced. That attachment or portion of the pumping T which provides the packing around the reciprocating rod is called a stuffing box, while that portion of the reciprocating sucker rod linkage which slides through the packing is called a polish rod.

In many of the known stuffing boxes, the sliding mve ment of the polish rod through the packing in the stufiing box generates a great deal of harmful frictional heating which may cause leakage through rapid wear or destruction of the packing material and which may also cause damage to the polish rod. Periodic inspection of such stuffing boxes is required to reduce production loss and damage to the pumping equipment which may occur when a rod has been destroyed or the packing begins to leak from wear. The frequent need to inspect and replace damaged rods or worn packing increases production expenses and contributes to costly periods of nonproduction.

Description of the prior art Certain prior art devices have attempted to reduce the undesirable frictional heating and Wear by lubricating the stuing box. Such prior art devices have generally been relatively complex and have not satisfactorily achieved the desired cooling and lubrication. Some of such devices have required external reservoirs of lubricating fluid which required frequent refilling or have required periodic inspection and attendance due to the relatively complicated apparatus employed. Another drawback in many of the prior art devices which have aternpted to reduce frictional 3,468,374 Patented Sept. 23, 1969 SUMMARY OF THE INVENTION The self-cooled stufng box of the present invention uses the high pressure in the production tubing to cause the production fluid to ow into a cooling chamber through an inlet supply line which is equipped with a one-way valve. A return line is connected to the production tubing to provide an outlet for the uid contained in the cooling chamber when the well pressure is reduced during the low pressure portion of the pumping cycle. A second oneway valve in the return line co-operates with the valve action in the inlet line to provide circulation of uid through the cooling chamber to carry away the frictional heat generated in the stuing box. The stuing box is also designed lto leave a reserve of uid in the cooling chamber to lubricate the polish rod during periods when the well is pumped dry or when the pump fails or where for any other reason there is no iluid present within the pumping T.

The relative simplicity of the stuing box ofthe present invention as well as its use of readily available components reduces the total cost of the box and also assures ease of installation as well as a lower frequency of repair rate. Due to the self-contained aspect of the stuing box of the present invention, periodic restocking of the lubricating fluid is not required. The stufling box of the present invention has an increased life and provides a minimum of lost production -time during the replacement of the packing or during the repair or initial installation of the equipment.

It is therefore an object of the present invention to provide an improved stung box which is self-lubricating and self-cooled. This object and other objects will become more apparent from the following description and drawings.

DESCRIPTION OF THE DRAWING The figure is an elevation partially in section illustrating the self-cooled oil well polish rod stuing box of the present invention mounted in position on a pumping T.

DESCRIPTION OF THE PREFERRED EMBODIMENT As illustrated in the figure of the drawing, the stuffing box of the present invention comprises a hollow metal body or housing indicated generally at 10 which is coaxially mounted about a section of polish rod R. Two packing chambers 10a and 10b are formed at the axial ends of the housing 10 and a cooling chamber 10c is centrally disposed between the packing chambers 10a and 10b. The packing chambers 10a and 10b have an interior cylindrical wall with threads 10d and 10e, respectively, formed at their outermost ends. The innermost ends of the packing chambers 10a and 10b abut packing stops 10Jc and 10g. The stops 10)c and 10g are centrally apertured at 10th and 10i, respectively, with the openings having diameters greater than the diameter of the rod R to prevent any metal to metal contact between the housing 10 and the moving rod R. The cooling chamber 10c is cylindrically shaped with the diameter of the interior cylindrical surface of the chamber 10c being greater than the internal diameter of the packing chambers 10a and 10b.

The packing chambers 10a and 10b contain several stacked sections of split ring asbestos packing P which r-mly engage the polish rod R to form a seal between the moving rod R and the housing 10. The packing P is held in compression in the chamber 10a by a packing collar 11 to torce the packing P to bear tightly against the outer surface of the rod R. The packing col'lar 11 is equipped with threads 11a which mate with the internal threads d of the packing chamber 16a. The collar 11 may be removed from the housing 10 or adjusted to alter the compression of the packing P with the assistance of a Wrench or the like acting on a wrench surface which is provided on the collar at 11b. A lock ring 12 with internal threads 12a engages the threads 11a of the collar 11 to prevent undesired movement of the collar 11 with respect to the housing 10. The lock ring 12 is equipped with an external wrench surface 12b to assist in tightening the ring against the housing 10.

The packing P in the packing chamber 10b is held in position with a threaded adapter nipple 13 having threads 13a which engage the internal threads 10e of the lower packing chamber 10b. The adapter nipple 13 is locked in position by a lock ring 14 having threads 14a which engage the threads 13a of the adapter nipple 13. The lock ring 14 is provided with wrench surfaces 14b to which a Wrench may be applied `to assist in securing the ring 14 against the housing 10.

The lower end of the adapter nipple 13 is provided with threads 13b which engage internal threads 11411 formed in the upper end of a pumping T 114. A central unthreaded body portion of the adapter nipple 13 is tapped by two smaller threaded nipples 15 and 16. One end of the nipples 15 and 16 communicates with the interior of the adapter nipple 13 to prov-ide an access opening between the fluid contained within the adapter nipple 13 and the cooling chamber 10 while the second ends, respectively, of the nipples 15 and 16 engage the control valves 17 and 18. The opening through the valve 17 may be adjusted or entirely closed by rotating the handle 17a. Similarly, rotation of the handle 18a adjusts or closes the valve opening in the valve 18.

The nipple 15 and valve 17 form the first part of an inlet supply line indicated generally at 19. The supply line 19 carries the production uid contained within the adapter nipple 13 to the cooling chamber 10c. A one-way check valve 20 is connected between the valve 17 and a small T fitting 21 to permit the production huid to iiow only in the direction of the arrow. The T fitting 21 carries a standard grease fitting 22 for a purpose to be hereinafter described. The upper end of the T fitting 21 is connected to a high pressure, flexible line 23 which in turn is connected to an elbow 24. The elbow 24 opens into the approximate mid point of the interior of the cooling chamber 10c.

The nipple 16 and valve 18 form a portion of a return line, indicated generally at 25, which conducts uid from the interior of the cooling chamber 10c to the interior of the adapter nipple 13. The valve 18 is connected to a oneway check valve 26 which permits the production fluid to flow only in the direction of the arrow. The upper end of the check valve 26 is connected to a high pressure exible line 27 which in turn is connected to an elbow 28. The elbow 28 opens through the housing 10 into the upper end of the interior of the cooling chamber 10c.

In the operation of the self-cooled stufiing box 10 Of the present invention, the pump placed in the oil well is driven by a pumping jack (not shown) causing the polish rod R to reciprocate vertically through the box 10. As the rod R moves on the upward stroke of its cycle, the pressure of the fluid (which includes gas and air bubbles) within the pumping T 114 increases and forces fluid through the check valve 20 in the supply line 19 and into the cooling chamber 10c. On the downward stroke of the pumping cycle, the pressure in the pumping T decreases and the higher pressure of the gas and nid in the cooling chamber 10c causes a portion of its contents to ow back into the pumping T.

The iiuid in the chamber 10c lubricates a section of the rod R as it reciprocates through the chamber. The lubrication is carried along the rod to reduce the friction and resultant frictional heating and wear caused by the rubbing seal action ot' the packing P against the rod R. The stuffing box l0 and rod R are cooled by uid from the production tubing which enters the chamber 10c through the supply line 19 where it is heated by the frictionally generated heat in the box 10 and rod R and is then carried away from the chamber 10c through the return line 25.

The valves 17 and 18 may be adjusted as desired to regulate the rate of fluid circulation through the cooling chamber 10c. lf desired, the valves 17 and 18 may be completely closed to permit testing, inspection, or repair.

As illustrated in the drawing, the return line 25 communicates with the upper end of the interior of the cooling chamber l0. When for any reason the pumping action should fail to provide duid at the interior of the nipple 13, the tiuid below the level of the upper end of the line 25 in the cooling chamber 10c forms a reservoir of iiuid which continues to provide lubrication for the moving rod.

The grease fitting 22 is a standard tting having a one-way action which permits lluid to be introduced into the T fitting 21 and supply line 19 but prevents an opposite escaping liow of the contents of the T. The grease fitting 22 is used to prime the chamber 10c with a lubricating iluid after the initial installation of the stufiing box 10, or it may be employed to supply the cooling chamber 10c with a lubricant when there is no production fluid in the nipple 13.

Replacement of the worn packing P in the upper packing chamber 10a is easily effected by simply closing the valve 17 releasing the lock ring 12 and unscrewing the packing collar 11 from the housing 10. The collar 11 and ring 12 are lifted up along the rod R; the worn packing is removed from the packing chamber 10a and replaced with new packing. The packing P is preferably in the form of semicircular ring segments so that the packing may be placed in the packing chamber without removal of the rod R. When the desired number of layers of new packing P have been placed in the packing chamber 10a, the collar 11 is threaded back into the housing 10 and secured by the lock ring 12.

The replacement procedure for the packing P in the lower packing chamber 10b requires that the pumping action be stopped, the flow line closed off, and the pressure in the production tubing reduced. The supply line 19 and return line 25 are separated to break the linkage between the adapter nipple 13 and the housing 10. The lock ring 14 is then loosened and the housing 10 is unscrewed from the threads 13a of the adapter nipple 13. The housing 10 may then be lifted up along the rod R to permit the worn packing P to be replaced. The housing 10 is then rethreaded onto the adapter nipple 13 and secured by tightening the lock ring 14.

While only the preferred form of the invention has been described herein, it is understood that various changes may be made in its construction `by those skilled in the art without departing from the spirit of the invention. Thus, by way of example rather than limitation, by minor adaptation, the nipples 15 and 16 may be connected into the lower portion of the housing 10 rather than the adapter nipple 13 so that the packing in the lower chamber 10b may be removed without first separating the supply line 19 and the return line 25; the elbows 24 and 28 may be introduced into the cooling charnber 10c at different levels to alter the amount of fluid exchange during each pumping cycle to thereby change the rate of cooling or the level of the lubricating reservoir. Certain elements of the described structure may be omitted without altering the principle of operation of the device although in the preferred embodiment al1 of the basic elements described are desirable.

I claim:

1. A self-cooled stuliing box comprising:

(a) housing means disposed above a pumping T for receiving a polish rod recprocably movable therein;

(b) first and second longitudinally spaced packing chambers formed in said housing means and each having packing therein for sealing engagement with said polish rod;

(c) a central cooling chamber formed in said housing means disposed between said first and second packing chambers;

(d) a supply line having first and second ends with said first end of said supply line communicating with the interior of said cooling chamber and with said second end communicating with the interior of said pumping T for supplying fluid therefrom upon longitudinal movement of said polish rod in one direction;

(e) a return line having first and second ends with said first end of said return line communicating with the interior of said cooling chamber and with said second end communicating with said interior of said pumping T for returning fluid from said chamber to said pumping T upon longitudinal movement of said polish rod in the opposite direction;

(f) one-way check valve means between said first and second ends of said supply line for permitting uid fiow through said supply line in only the one direction from said pumping T to said cooling chamber; and

(g) one-way check valve means between said first and second ends of said return line for permitting fluid fiow through said supply line in only the one direction from said cooling chamber to said pumping T.

2. The self-cooled stufng box as defined in claim 1,

including:

(a) adapter nipple means secured to the lower end of said housing means for connecting said housing means for connecting said housing means to said pumping T;

(b) means for communicating said second end of said supply line with the interior of said pumping T through said adapter nipple means; and

(c) means for communicating said second end of said return line with the interior of said pumping T through said adapter nipple means.

3. The self-cooled stuffing box as defined in claim 2,

including:

(a) internally threaded surfaces on said first and second packing chambers;

(b) a packing collar having external threads engaging the internal threads of said first packing chamber; and

(c) external thread means formed on said adapter nipple means for engagement vWith the internal threads of said second packing chamber.

4. The self-cooled stufiing box as defined in claim 3,

including:

a control valve means between the first and second ends of said supply line for manually regulating the rate of fiuid fiow through said supply line.

5. The self-cooled stuffing box as dened in claim 3,

including:

a control valve means between the first and second ends of said return line for manually regulating the rate of fluid flow through said return line.

6. The self-cooled stuffing box as defined in claim 4,

including:

a control valve means between the first and second ends of said return line for manually regulating the rate of fluid ow through said return line.

7. Theself-cooled stuing box as defined in claim 6,

including:

(a) first and second lock rings having internal threads engaging the external threads of said packing col1ar and the external threads of said adapter nipple means, respectively; and (ib) a grease fitting between said first and second ends of said supply line.

y References Cited UNITED STATES PATENTS 2,567,479 9/ 1951 Hebard 277-3 3,395,923 8/1968 Remke et al 277--59 1,479,304 l/1924 Krogh 184-6 2,079,922 5/1937 Owen 166-84 3,297,091 1/1967 Dale 166-84 3,353,606 ll/1967 Dyer 166-84 FRED C. MATTERN, JR., Primarsl Examiner M. ANTONAKAS, Assistant Examiner U.S. Cl. X.R. 184-6; 277-15 

